Air conditioning apparatus



Dec. 6, 1966 J. L. KLINE 3,289,746

AIR CONDITIONING APPARATUS Filed Sept. 28, 1964 INVENTOR.

JOHN L. KLINE ATTORNEY United States Patent G 3,259,746 AIR.CONDHTIGNING APPARATU John L. Kline, Louisville, Ky., assignor toAmerican Air Filter Company, Inc, Louisville, Ky., a corporation ofDelaware Filed Sept. 28, 1964, Ser. No. 399,4a 4 Claims. (#01. 165-36)This invention relates to air-conditioning apparatus of the fan-coiltype, and more particularly to a control arrangement therefor.

Fan-coil units are typically used to heat or cool a conditioned space bypassing air through a heat exchange coil which usually receives hot orchilled water generated at a remote location and piped to the fancoilunit. One commonly used means for controlling the discharge airtemperature of the fan-coil unit to meet the temperature demands of theconditioned space has involved the use of a valve controlling the flowof water to the coil in accordance with variations in temperature of theconditioned space. This so-called valve control has for the most partbeen favored over an alternate type of control termed face and bypassdamper control because it permits a more compact fan-coil unit than adamper control arrangement since no space for a bypass passage and adamper therein is required.

However, if valve control is compared with damper control from astrictly technical standpoint with respect to temperature and humiditycontrol of the air, many believe that a damper control arrangementprovides superior results. This is particularly true with respect to theproblem of providing continued moisture removal from the air passingthrough the unit at times when there is no corresponding requirement forthe unit to exert its full cooling capacity. For example, with one typeof valve control using a single valve which modulates in accordance withroom temperature variations, the typical flow characteristics of thevalve results in an early reduction in quantity of chilled wateradmitted to the coil with slight reduction in cooling demand of theroom. The resulting higher surface temperature of the coil results in asharply reduced moisture removal capacity and the ultimate evaporationof condensate from the coil surface with a concomitant release ofconcentrated odors.

An alternate type of valve control is the so-called multi-port valvecontrol. Here the coil is divided into separate circuits with eachcircuit being fed through a separate port of the valve. Thus successiveportions of the coil are deprived of the chilled water as the coolingdemand in the room is reduced. The theory is that the circuits receivingchilled water will continue to remove adequate moisture fordehumidifying purposes. In addition to the fact that separate circuitcoils and multi-port valves are both relatively expensive, a furtherdisadvantage of such an arrangement is that those parts of the coilwhich are deprived of chilled Water as the successive circuits of thecoil are cutoff Will Warm up and release concentrations of odors.Further, even though the multi-port valve is of the character that eachsection is of the modulating type, unless the sections of the coilitself are physically isolated and separated from each other, theinfluence of one extends to the other sections. As a result even thepart of the coil which continues to receive chilled Water has a highersurface temperature than it would have if unconnected physically to theother parts of the coil.

In summary then, the disadvantage with respect to humidity controlstemming from valve control, as contrasted to damper control, is that ascooling requirements are reduced in the room there is a reduction oftemperature differential between the coil and the air going through thecoil. This increases the likelihood that the surface of the coil willbecome warmer than the dew point of the air so that the coil then notonly does not remove moisture from the air passing through it but infact may release moisture to the air.

In contast with a valve control arrangement, a damper controlarrangement results in .a coil surface temperature which actuallydecreases as the temperature demands of the room for cooling decrease.This results from a continued full flow of chilled water with a reducedair flow through the coil. Consequently, that part of the air which isdirected through the chilled coil is subject to greater dehumidificationthan if the demand of the room for cooling were greater. While thisadvantage of damper control over valve control for purposes ofdehumidification is generally accepted in the art, it is substantiallynullified when the bypass damper reaches a closed position so that noair passes through the coil. In other words, when there is very littledemand for cooling, the closed damper prevents the air from contactingthe coil and therefore from being dehumidified.

The present invention provides an. arrangement in which the advantagesof damper control are not lost when the damper approaches its extremeclosed position. Further, the arrangement according to the inventionfacilitates a compact arrangement of parts in a fan-coil type of unit asrequired by the market for such units. In accordance with thearrangement of the invention, the face and bypass damper provided isdimensioned so that in its fully-closed position it extends over andcovers a major portion of, but substantially less than, the entire facearea of the coil. Accordingly, even while the damper is in a rangeapproaching .a fully-closed position against the face of the coil, airflow through the coil, and accordingly dehumidification, continues. Whenunder these conditions the cooling requirements of the conditioned spaceare fully met, a simple on-off valve controlling the flow of temperingmedium to the coil is actuated to a closed position to prevent coolingbeyond the desired point.

The arrangement not only provides substantial advantages in a coolingcycle operation (chilled water), but also operates quite satisfactorilyduring the heating cycle when the unit receives hot Water. Obviously,dehumidification is not a problem during the heating season, andconsequently the continued flow of air through the coil when the damperis fully closed does not have the significance in the winter heatingseason that it does in the summer cooling season. In the case of thecoil receiving hot water, after the damper has removed to a fully-closedposition indicating the temperature demands of the room are met, thesame on-oif valve is actuated to a closed position. Thus, any furthertemperature pick-up is avoided, providing in a sense an advantage overthe conventional damper control arrangements which have no valve.

The invention will be explained in some detail in connection with theaccompanying drawing wherein:

FIGURE 1 is a partly broken front elevational view of a floor modelfan-coil unit with certain principal interior parts being shown inbroken-line outline form;

FIGURE 2 is .a somewhat diagrammatic view in the nature of a verticalsection corresponding to one taken along the line 2--2 of FIGURE 1;

FIGURE 3 is a fragmentary elevational view inside an end compartmentshowing one example of an arrangement for a damper motor and othercontrol elements.

The floor model unit illustrated in FIGURES 1 and 2 is disposed with'its back side against room Wall 10 and its bottom resting upon floor12. The interior of the unit is divided generally into left-hand andright-hand end compartments 14 and 16, respectively, on opposite sidesof the center compartment 18 defined between opposite end verticalpartitions 19 and 21. Piping, electrical and control components areaccommodated within the end compartments, while the center compartmentgenerally defines the path for the how of air to be treated and containsthe principal elements for so treating the air.

Air to be conditioned is drawn into the lower part of the centercompartment 18 through an outdoor air inlet 20 and a room air inlet 22by fans 24. After passing through a filter 26, the air is dischargedupwardly by the [fans toward the extended surface heat exchange coil 28.Depending upon the position :of the face and bypass damper 30, the airwill pass through the coil, or through the adjacent bypass passage 32,or as a third alternative, partly through the coil and partly throughthe bypass passage if the damper is in intermediate position. Theconditioned air is then discharged from the center compartment into theconditioned space through the outlet grille area 34. Of course the airpassing through the coil is tempered in accordance with the character ofthe tempering medium in the coil, and in this sense the passage definedby the coil perimeter may be said to .be an air tempering passage.

The fans 24 and drive motor 36 therefor are mounted on an inclined motorboard 38 having openings therein in the rear part to accommodate thedischarge of the fans. The forward part 40 of the board which underliesthe bottom edge of the coil 28 serves as a drip pan for moisturecondensed from the air and which drips from the coil onto the pan. Theinclined disposition of the motor board and the generally illustrateddisposition of the fan housings as best shown in FIGURE 2 savesubstantial space with respect to both height and depth of the unit andalso automatically result in the desirable corresponding inclination ofthe drip pan 4!) portion of the motor board.

As best illustrated in FIGURE 2, the coil 28 is inclined generally asshown with its lower edge adjacent the front of the fan-coil unit, andits upper edge closer to the rear of the unit, and with the upper rearcorner 42 of the coil frame defining the forward boundary of the bypasspassageway 32. Thus, the air entering face 43 of the coil is in a planelying at an acute angle with respect to the usually vertical front andrear walls of the unit. The bypass damper 30 is pivotally mounted on ashaft 45 which extends between the opposite end compartments along aline parallel to and closely adjacent this forward boundary of thebypass passageway 32.

The bypass damper 30 is as wide as the coil 28, but has a heightdimension which is only about three-fourths of the height dimension .ofthe air entering face 43 of the coil 28. Thus, as best shown by thebroken-line outline in FIGURE 2, when the damper 30 is in its extremeposition against the air entering face of the coil, the damper coversonly about three-fourths of this face area of the coil with about thelower cne fourth of the face area being open to receive air flow throughthe coil. The arrangement in which the lower portion of the coil face isleft open is preferred since the supply of water is first supplied tothe lower part of the coil. It will be also noted that the exposed lowerpart of the coil is closer to the cutoff part of the centrifugal fan 24than the part of the fan outlet adjacent the rear side of the unit.

To connect the unit for service, piping connections are made in one endcompartment with the electrical connections and damper motor in theopposite end compartment. As illustrated in FIGURE 1, the right endoompartme-nt 16 contains a solenoid valve 44 in the water supply line 47to the coil 28. An electrical line 46 extends from the solenoid valve toa switch 48 in the left end compartment 14 for cont-rolling theactuation of the valve 44.

As seen in FIGURE 3, the electrical switch 48 includes an operator arm50 disposed in the path of movement of the end of an actuating lever 52secured to the damper shaft so as to turn therewith. The lever 52extends from the shaft in substantial alignment with the damper 30 shownin broken-line outline in FIGURE 3. The position shown corresponds toone in which all of the air is directed through the coil as if the roombeing served were demanding the full capacity of the unit. To effectmovement of the damper shaft 45, a damper operator 54 is provided withits linkage arrangement 56 connected to the shaft 45. The operator maybe of any of the well-known types.

Positioning of the bypass damper 30 is controlled in accordance withroom temperature variations. Specifically, assuming the unit isoperating in a cooling cycle, the system is arranged so that the damperis moved in a direction to block the bypass passage 32 upon a demand forcooling, and in the other direction to block the coil upon a decreaseddemand for cooling. The preferred arrangement is such that the damper ismoved in modulating fashion as distinguished from two-position movement.The arrangement gives, within limits, an increasing proportion of airdirected through the coil or tempering passage 28 upon an increase inroom temperature above the set point, and an increasing proportion ofthe air directed through the bypass passage 32 upon a decrease in roomtemperature below the set point.

While the damper 30 is in its range of modulating movement, solenoidvalve 44 remains in its normal open position giving full flow of chilledwater through the coil. However, when the demand for cooling in the roomis substantially satisfied, the movement of the damper to acorresponding position si-g-nals the satisfaction of the demand byreaching a position substantially against the face of the coil. In thisposition, lever 52 engages the actuating arm cf the valve switch 48 soas to cause the solenoid valve to close and out off chilled water to thecoil. If thereafter additional cooling is required for the conditionedspace, the movement of the damper back away from the face of the coilwill result in the solenoid valve 44 again opening to permit the flow ofchilled water to the coil.

The temperature control requirements of a typical installation areusually adequately satisfied by arranging for the switch 48 to beactuated to a valve-closing position during the final increment oftravel of the bypass damper against the face of the coil. 'For example,the parts may be disposed so that when the damper 30 reaches a pointabout five degrees away from the coil face, the switch will be actuated.However, in some circumstances it may be desirable that the damper 30 beable to move to a final position against the face of the coil withoutautomatically effecting closure of the solenoid valve 44 in thatposition. In other words, .it may be desirable that there be a furtherincrease in room temperature required after the damper 30 is in itsfinal position before the valve 44 is closed. This may be provided, ifdesired, in any of several different ways, one of which may be theprovision of a spring-loaded connection between the lever 52 and thedamper shaft to permit the lever to have an increment of over-travelafter the damper 30 reaches its extreme position against the face of thecoil.

The description of the operation has proceeded with chilled water beingthe principal tempering medium example. In a heating cycle, hot water issupplied with the operation being much the same except that the movement of the damper 30 is opposite to that described upon roomtemperature increases and decreases.

As noted before, the provision of the valve 46 to cut off the supply ofwater in the final position of the damper against the coil face reducedcabinet sweating in the summer, and temperature pick-up in the winter.In that connection, it is noted that a bypass damper control system isordinarily not completely effective in preventing all heat exchangebetween the bypass air and the coil. Thus, another advantage of theinstant arrangement is that the sealing requirements of the damper arenot as stringent since the final valve shutoif obviates the need.However, perhaps the principal advantage of an arrangement according tothe invention is experienced in the cooling cycle with the extendeddehumidification provided. Thus, as the damper moves toward the coilface, a colder coil face temperature automatically results. Consequentlyany air which passes through the coil is subjected to greater humidityremoval than if the coil were fully open to air flow. Further, with anarrangement in which there is always some air passing through the coil,drying of the coil surface at a time when concentrated odors wouldpresent a problem is practically precluded.

I claim:

1. An air-conditioning apparatus comprising:

a casing including means defining a path for the flow of airtherethrough, and including a recirculation air inlet and an air outletin communication with said path;

means for inducing a flow of air through said path;

heat exchanger means extending substantially along the length of saidpath and across a part of the width of said path;

a bypass passage adjacent a downstream edge of said heat exchanger meansfor air to pass around said heat exchanger means;

damper means extending along the length of said air flow path andpivoted adjacent said downstream edge of said heat exchanger means tomove into a stream of air flowing through said path to one extremeposition entirely closing said bypass passage, and to move to anopposite extreme position covering at least a major portion butsubstantially less than all of the face of said heat exchanger means;and

means for terminating the flow of the tempering medium to said heatexchanger means in response to said damper means moving to said oppositeextreme position.

2. Air-conditioning apparatus comprising:

means defining a path for the flow of air to be treated;

a heat exchange coil disposed with its face extending substantiallyalong the length of said path and across part of the width of said pathto divide said path into an air tempering passage for air passingthrough said coil, and a bypass passage adjacent a downstream edge ofsaid coil;

bypass damper means for controlling the flow of air through saidpassages, said bypass damper means extending substantially along thelength of said air path and pivoted along said downstream edge of saidheat exchange coil to move into said stream of air to one extremeposition sealing said bypass passage to prevent flow therethrough, andto move to an opposite extreme position in which more than half butsubstantially less than all of said coil face is blocked; and

means responsive to the position of said damper means in said latternoted position to completely terminate the flow of tempering medium tosaid coil.

3. Air-conditioning apparatus according to claim 2 in which:

said coil is inclined with its said face extending at an acute anglewith respect to the parallel planes coincident with the front and rearwalls defining said path; and

said bypass damper means is pivotally mounted along the upper edge ofsaid coil dividingsaid path into said tempering passage and said bypasspassage.

4. Air-conditioning apparatus according to claim 3 in which:

said bypass damper means is of substantially less height than the heightof said coil face so that the bottom part of said coil face remains opento air flow in said opposite extreme position.

References Cited by the Examiner UNITED STATES PATENTS 2,327,663 8/1943Otis -122 2,828,110 3/1958 Baker et a1 165-103 3,129,753 4/1964 Davis etal 16536 FOREIGN PATENTS 379,430 9/1952 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

